[TASK] Deprecate BackendUtility::getHash/storeHash

The methods are only wrappers for the Caching framework, and come
from the time where the caching framework wasn't available.

Resolves: #83116
Releases: master
Change-Id: I6e3293f1bde654ee6548898742daa77d044d2107
Reviewed-on: https://review.typo3.org/54758


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Susanne Moog <susanne.moog@typo3.org>
Tested-by: Susanne Moog <susanne.moog@typo3.org>